Japanese Unexamined Patent Application Publication No. 2001-254886 discloses a pipe coupling including a female pipe coupling member and a male pipe coupling member. The female pipe coupling member includes a generally cylindrical female member body, a locking element hole formed so as to extend through the female member body in the radial direction of the female member body, a locking element displaceable in the locking element hole, and an outer cylindrical member that forms an annular sleeve receiving portion between an outer peripheral surface of the female member body and the outer cylindrical member and prevents the locking element from being dislodged from the locking element hole. The male pipe coupling member includes a generally cylindrical male member body configured to be inserted into the female member body, and a sleeve provided around the outer periphery of the male member body so as to be slidable and urged forward by means of a spring. When the male member body is inserted into the female member body to a position where an engaging groove formed on an outer peripheral surface of the male member body aligns with the above-described locking element in the radial direction of the male member body, the sleeve is moved forward by a spring urging force while displacing the locking element radially inward to fit the locking element into the engaging groove. The sleeve is then displaced to a position radially outward of the locking element to lock the locking element in the engaging groove. Thus, the female pipe coupling member and the male pipe coupling member are coupled to each other.